Method and system for generating shaded pictures

ABSTRACT

A METHOD FOR USE IN A COMPUTER FOR GENERATING SHADED RENDERINGS OF A SCENE WHICH COMPRISES THE TREATING OF EACH SURFACE IN THE SCENE AS A PLURALITY OF HORIZONTAL SCAN LINES AND THE TREATING OF EACH SCAN LINE ON A SURFACE AS A PLURALITY OF SEGMENTS. IN A FIRST EMBODIMENT OF THE METHOD, THERE ARE PROVIDED SPECIFIC VALUES FOR ILLUMINATION INTENSITY FOR EACH SURFACE AND RANDOM NUMBER VALUES, THE MINIMUM RANDOM NUMBER VALUE BEING LESS THAN OR EQUAL TO LOWEST VALUE ILLUMINATION INTENSITY VALUE FOR ANY OF THE SURFACES. AS A SEGMENT OF A LINE IS CONSIDERED, THE ILLUMINATION INTENSITY OF THE SURFACE IT FALLS ON IS COMPARED WITH THE RANDOM NUMBER CONCURRENTLY BEING GENERATED. IF THE RANDOM NUMBER IS LESS THAN ILLUMINATION INTENSITY, THEN THE LINE SEGMENT IS DRAWN, I.E., ILLUMINATED. HOWEVER, IF THE RANDOM NUMBER CONCURRENTLY EXCEEDS THE   GENERATED SEGMENT&#39;&#39;S ILLUMINATION INTENSITY, THEN THE SEGMENT IS NOT DRAWN, I.E., NOT ILLUMINATED. IN A SECOND EMBODIMENT, EACH SEGMENT IS PROVIDED WITH A VALUE WHICH IS THE SUM OF ITS ORTHOGRAPHIC OR PERSPECTIVE PROJECTION COORDINATES, X AND Y. IF THE ILLUMINATION INTENSITY OF THE SURFACE ON WHICH THE SEGMENT BEING CONSIDERED CURRENTLY LIES FALLS WITHIN A CHOSEN RANGE OF COORDINATE SUMS AND IF THE SUMS OF THE X AND Y COORDINATES OF THE SEGMENT IS AN INTEGER MULTIPLE OF A FUNCTION OF THE ILLUMINATION INTENSITY OF THE SEGMENT, THEN THE SEGEMENT IS DRAWN.

DEFENSIVE PUBLICATION UNITED STATES PATENT OFFICE Published at the request of the applicant or owner in accordance with the Notice of Dec. 16, 1969, 869 O.G. 687. The abstracts of Defensive Publication applications are identified by distinctly numbered series and are arranged chronologically. The heading of each abstract indicates the number of pages of specification, including claims and sheets of drawings contained in the application as originally filed. The files of these applications are available to the public for inspectionand reproduction may be purchased for 30 cents a sheet.

Defensive Publication applications have not been examined as to the merits of alleged invention. The Patent Oflice-makes no assertion as to the novelty of the disclosed subject matter.

PUBLISHED JULY 24, 1973 REGIONS IN SHADOW N0 ILLUMINATION REGIONS IN SIIMJO' N0 ILLUMINATION A method for use in a computer for generating shaded renderings of a scene which comprises the treating of each surface in the scene as a plurality of horizontal scan lines and the treating of each scan line on a surface as a plurality of segments. In a first embodiment of the method, there are provided specific values for illumination intensity for each surface and random number values, the minimum random number value being less than or equal to lowest value illumination intensity value for any of the surfaces. As a segment of a line is considered, the illumination intensity of the surface it falls on is compared with the random number concurrently being generated. If the random number is less than illumination intensity, then the line segment is drawn, i.e., illuminated. However, if the random number concurrently exceeds the generated segments illumination intensity, then the segment is not drawn, i.e., not illuminated. In a second embodiment, each segment is provided with a value which is the sum of its orthographic or perspective projection coordinates, X and Y. If the illumination intensity of the surface on which the segment being considered currently lies falls within a chosen range of coordinate sums and if the sums of the X and Y coordinates of the segment is an integer multiple of a function of the illumination intensity of the segment, then the segment is drawn.

July 24, 1973 A. APPEL T A T912012 METHOD AND SYSTEM FOR GENERATING SHADED ILIITURES l6 Sheets-Sheet 1 Filed June 30, 1972 1 FIG. I

RANDOM TECHNIQUE AREAS IN SHADOW MINIMUM ILLUMINATION DIM LY ILLUM INATED BRIGHILY ILLUMI N ATED FIG. 2

LINE DENSITY SHADING AREAS IN SHADOW NO ILLUMINATION BRIGHTLY ILLUMINATED DIM I Y ILLUMINATED July 24, 1973 A. APPEL ET AL T912312 METHOD AND SYSTEM FOR GENERATING SHADED PICTURES Filed June 30, 1972 16 Sheets-Sheet 2 FIG. 3

' REGIONS IN SHADOW NO ILLUMINATION REGIONS IN SHADOW NO ILLUMINATION July 24, 1973 A. APPEL ET AL METHOD AND SYSTEM FOR GENERATING SHADED PICTURES Filed June 30, 1972 IO\.. INITIALIZE DISPLAY READ vERTEx LIST DE ALL PDINTs IN SCENE READ TOPOLOGICAL MAP OF ALL oBIEcTs IN SCENE COMPUTE AND STORE ALL SURFACE EQUATIONS cDMPuTE AND sTDRE ALL LINE EDLIATIDNs CALCULATE DIRECTION OF SUR- 2o FACE NORHALS SUCH THAT THE E NORHALS POINTS INTO THE VOL- UNES OF EACH OBJECT 16 Sheets-Sheet 5 READ IN LOCATION OF 22 VIEWPOINT EX,EY,EZ

CALCULATE PERSPECTIVE PROJECTION OF EACH POINT IN SCENE AND STORE FIG. FIG .4 4A

Fl G 4A W FIG. 4:: FIND AND STORE THE MINIMUM VALUE OF DY,DYMIN FIND AND sToRE THE MAxIMDM VALUE OF DY, DYMAX READ IN LOCATION 0E LIGHT 50 SOURCE sxrmsz DETERMINE WHICH SURFACES FACE AWAY ERDM THE OBSERVER ,52

AND sToRE IN A TABLE DE POTENTIAL VISIBILITY CALCULATE AND sToRE THE COSINE OF THE ANGLE EACH /s4 SURFACE MAKES WITH A LIGHT RAY To THE FIRST PDINT LIsT- ED AS BEING DN EACH SURFACE DETERMINE WHICH SURFACES FACE AWAY FROM THE LIGHT AND 36 sToRE IN A TABLE OF POTENTIAL ILLDMINATIDNs I DYP -DYMIN A8 July 24, 1973 A. APPEL ETAL T912,012

METHOD AND SYSTEM FOR GENERATING SHADED PICTURES Filed June 30, 1972 16 Sheets-Sheet 4.

4 V, 0YP-DELY DYP 7 4B 42 IS DYP DYMAX STOP YES FORM A SCAN PLANE IN SPACE WHICH CONTAINS THE VIEWPOINT AND THE HORIZONTAL LINE ON THE PICTURE PLANE WITH Y-DYP 46w J Q 51 48 L J J+1 BREAK LINE ICJ INTO SEGMENTS so v WHICH ARE VISIBLE L 0R INVISIBLE NO YES IS PV(J)=1? 5s YES 4 NO FIND THOSE SEGMENTS OF ME Y'S' DOES DYP FALL WITHIN THERANGE n 0F 0v 0F POINTS 0N SURFACEJ? YES N0 ARE THERE VISIBLE SEG MEWS OF LINE ICJ FIND THE LINE OF LNTEHsEcTLoN A OF SURFACE J WITH THE CURRENT No YES I L SCAN PLANE l y Y July 24, 1973 A. APPEL ET AL METHOD AND SYSTEM FOR GENERATING SHADED PICTURES Filed June 30, 1972 IS PIIJ)=1? /-62 64 YES NOL DETERMINE WHICH SECMENTS OF ICJ ARE ILLUMINATED AND WHICH ARE IN THE SHADOW OF OTHER OBJECTS FORM A DISPLAY TABLE OF THE VISIBLE SECMENTS.

CLASSIEY SECMENTS AS TO WHETHER /66 16 Sheets-Sheet 5 DRAW ON THE DISPLAY DEVICE A HORIZONTAL LINE FROM XIIL) TO XZILI WITH Y=DYP OF INTENSITY H=h x SAIJ I x HMAX DRAW ON THE DISPLAY DEVICE y A HORIZONTAL LINE FROM X1(L) To X2(L) HE SEGMENT IS IN SHADOW OR IS ILLUHINATED WITH Y-[ziYfHaFlNlNTENslTY PROJECT THE LINE SEGMENT 0N To 68 THE PICTURE PLANE AND sToRE THE X-COORDINATES OF THE ENDPOINTS IS SEGMENT L THE LAST /80 SEGMENT 0N SURFACE J I 0 fm NO YES I I FIG. 40 PHI /?2 IS SEGMENT L IN SHADOW YES NO I July 24, 1973 A. APPEL ET AL T9l2,0l2

METHOD AND SYSTEM FOR GENERATING SHADED PICTURES Filed June 30, 1972 l6 Sheets-Sheet 6 OBJECTS IN EX SCENE July 24, 1973 A. APPEL ETAL T912,012

METHOD AND SYSTEM FOR GENERATING SHADED PICTURES Filed June 30, 1972 16 Sheets-Sheet '7 PICTURE PLANE LINE OF SIGHT FROM E T0 P P (TYPICAL POINT) FIG.8

July 24, 1973 APPEL ETAL T912,012

METHOD AND SYSTEM FOR GENERATING SHADED PICTURES Filed June so, 1972 16Sheets-Sheet 8 Fl LINE OF SIGHT T0 FIRST POINT ON 54 LINE OF SIGHT T0 FIRST NORMAL T0 POINT ON 51 SURFACE s1 NORMAL T0 SURFACE S4 FIG.1OC

July 24, 1973 APPEL ET AL T9l2,0l2

METHOD AND SYSTEM FOR GENERATING SHADED PICTURES Filed June so, 1972 1e Sheets-Sheet 9 VIEWPOINT TYPICAL SCAN PLANE PICTURE PLANE FIG.12

/ TYPICAL OBJECTS \ij IS VISIBLE jk IS HIDDEN July 24, 1973 A. APPEL ETAL T912,012

METHOD AND SYSTEM FOR GENERATING SHADED PICTURES Filed June 30, 1972 16 Sheets-Sheet 10 FIG. 13

TTYPICAL OBJECTS LIGHT SOURCE ij, kl,mn ARE ILLUMINATED jk,lm ARE IN SHADOW PICTURE PLANE SURFACEBEING 2 SCANNED 5 SHADOW OF OBJECTK -0BJECTK --LIGHT SOURCE VIEWPOINT 5 E F|G.|4

July 24, 1973 P E ETAL T912,012

METHOD AND SYSTEM FOR GENERATING SHADF-D PICTURES Filed June 30, 1972 16 Sheets-Sheet 11 x1(1 x2 1) x1(2) x2(2) x1 3 x2 3 l r 2 j v J PICTURE PLANE SEGTENT SEGMENT FIG. 15

280 COMMAND T0 DRAW LINE OF INTENSITYH FROM (X1,Y T0 X2,Y) 288 r 282 SUBTRACT iFROMH STORE H 286 284 GENERATE LINE OF INTENSITY1 HM? FROM(X1,Y) T0(X2,Y)

NO YES GENERATE LINE OF INTENSITY H 1 GO To FROM (X1,Y) T0 (X2,Y) L LINE 290 l 292 FIG. 22

July 24, 1973 Filed June 30, 1972 A. APPEL ET AL METHOD AND SYSTEM FOR GENERATING SHADED PICTURES 16 Sheets-Sheet 12 FIG. INITIALIZE DISPLAY DEVICE 001111101 moan/111,011 THE TRANSMISSION PROGRAM FIG-16 FIG mum-0 6B FIG. 16A

1 1 11/111 FOR REQUEST 1 0 102 DRAW 11011120111111 1111 OF E 1111511911111 11.

FETCH H,X1(L),X2(L) AND Y FROM 14/1111 PROGRAM -/1O4 110x an m -1oe IY-SFx Y 112 1s NX NDX? #414 NO YES IX-IXS+NX-JDX H8 IS ISTART=1.7.

11o YES 154 1 1 152-\15TART 0 DRAW A HORIZONTAL ho LINE 111011 (IXLIY) 10x RASTER 1111115 10111;

July 24, 1973 A. APPEL, ET AL T912,0l2

METHOD AND SYSTEM FOR GENERATING SHAW-ll) PICTURES Filed June 30, 1972 16 Sheets-Sheet 15 NO YES 124-HHH+ .04 HH'1.04H/-122 IX IY 12 4 In IFX IFY IH HHP /-12a FIG. 168

IS H .5? @150 IS 11x AN INTEGER fxm IS ITX AN INTEGER N132 MULTIPLE 0F IH MULTIPLE 0F IH NO YES YES NO 7 1s mm =1? M158 '315TART='?/-156 no YES YES lN L DRAW A HORIZONTAL 146 /140 LINE FROM (IX1,IY)

10x RASTER UNITS LONG 142 H ISTART 0 14a i 144 IDX 0 N150 IDX -IDX+JDX July 24, 1973 A. APPEL E T912312 METHOD AND SYSTEM FOR GENERATING SHADED PICTURES Filed June 30, 1972 16 Sheets-Sheet 14 1 PICTURE PLANE REAL COORDINATE SYSTEM FIG. 17A

TYPICAL POINT (o.o,o.o) .0)

PICTURE PLANE RASTOR COORDINATE SYSTEM FIG. 17 B TYPICAL POINT IDX FIG .19

(IX1,IY) (IX1+IDX,IY)

July 24, 1973 Filed June 30, 1972 FIG. 20

A. APPEL. ETAL T9l2,0l2

METHOD AND SYSTEM FOR GENERATING SHADED PICTURES l6 Sheets-Sheet 15 INITIALIZE DISPLAY DEVICE CONTROL PROGRAM 200 OR DATA TRANSMISSION PROGRAM.

WAIT FOR REQUEST TO DRAW HORIZONTAL LINE OF INTENSITY H.

FETCH H,XI(L),X2(L ANDY FROM MAIN PROGRAM 204 I SFx(XIIL)-X2IL)I zog NDX I IY--SFx Y 208 IXS-'SFxXI(L) 210 NX-O $21? I I I NX Nx+I -/2I4 IS Nx NDX YES NO my GENERATE A RANOOM NUMBER (RN) FROM 0.0 T0 1.0

220-J Is RN H I NO YES IXI -IXS+ NX X JDX 224- ORAw A HORIZONTAL LINE FROM (IX1,1Y)

JDX RASTER UNITS LONG wwmism U, V

July 24, 1973 A. APPEL ET AL METHOD AND SYSTEM FOR GENERATING SHADED PICTURES Filed June 30, 1972 LOADED BY PROGRAM X START REGISTER RAMP FOR GENERATING VALUES 0F X FROM XSTART T0 XEND I 232 [Ix ERO REGISTER 254 "I Y REGISTER COMPARATOR X DEFLECTION 1 16 Sheets-Sheet 16 ADDER 251 NO YES 247 SWITCH 247 H SUBTRACTOR 248 (IO-H) L /253 V H IO H FUNCTION GENERATOR 1Hf-252 DIVIDER R zss MULTIPLIER IHZ-RXITX J 259 COMPARATOR /26I SWITCH ISK 15R 263 i XOR 262 ISK ISR BEAM ELECTRON BEAM -26;

6 I I BEAM ON-I g BEAM OEF=O 

